ALSA: control: Fix a bunch of whitespace errors

Remove a bunch of trailing whitespace errors. They are
fairly annoying if you have your editor set to strip trailing
whitespace because you find you've introduced more changes
than you were trying to make.
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>